SOME ISSUES ON STATICS OF GEOMETRICALLY AND PHYSICALLY NONLINEAR CONTINUOUS MEDIUM

We consider the generalized plane deformation of physically and geometrically nonlinear continuous medium. The mathematical model of medium is described by physically nonlinear relations in the form of arbitrary cross dependences between the first invariants of tensors and the second invariants of stress and strain deviators, taking into account geometrical nonlinearity (according to V.V. Novozhilov). The system of resolving partial differential equations of equilibrium, done in displacements, is quasilinear. This type is being investigated. Despite the fact that the type of the system of quasilinear partial differential equations in a certain part of space can be determined only for a specific solution, it is stated that in the general case the system of differential equations of equilibrium of generalized plane deformation is a system of mixed type. The type of the system of partial differential equations in a given area of space is completely determined by the values of its coefficients, and therefore depends both on the value of physical constants of continuous medium material and also on the value of derivatives of displacements in spatial coordinates.